Stopping A Stink Bug Invasion

The quarantined, closet-sized room has its own ventilation system. The brown marmorated stink bug colony is kept inside an even smaller room within the lab.

Brown marmorated stink bug.Credit: WSU Photo Services

“So, here’s our colony,” says chemist Lee Ream, as he opens the door.

The stink bugs are kept in plastic containers. They fly around and eat the green beans, almonds, and figs Ream feeds them.

Ream is teaming up with other Northwest researchers to stop an invasion of stink bugs moving across the region. The problem with these non-native insects isn’t just that they they can smell like dirty gym socks. They also ruin tree fruit and grape vines, which are important Northwest crops.

A Voracious Appetite

Pockets of these invasive bugs have been found in Washington and Oregon. More are expected to fly into the area during the 2014 growing season.

That could become a real problem for area orchards, vineyards, and homes.

The brown marmorated stink bug is different from stink bugs native to the Northwest. This invasive bug eats pretty much any crop with sap – destroying any fruit it bites. It leaves brown pockmarks in apples, cherries, and blueberries, rendering the crops unsellable.

Ream breaks open an almond he had placed in the stink bug colony.

“You can actually see where there would be no damage on the outside of the almond, but on the inside, you can see where it’s decomposed. They’re actually soft and squishy,” Ream says.

On The East Coast

The brown marmorated stink bug is native to Asia. It first appeared in Pennsylvania in 1998 and has made its way across 40 states.

With no native predators, the bugs has become a big problem on the East Coast, where they overwinter in people’s homes.

“You go out to your house, you go out on the porch in November, and there are 1,000 of these things sitting on your porch with you. And they stink, and you’re stepping on them, and the dogs are eating them. So they become a real problem,” said Richard Zack, an entomologist with Washington State University.

Zack is on the research team that’s trying to fight the brown marmorated stink bug in the Northwest – before they start populating this region the way they have the East Coast.

Closer To Home

Zack said so far in the Northwest, the bugs been found in the Willamette Valley, along the Interstate-5 corridor and in Southwestern Washington.

The insects are slowly moving eastward toward the Yakima Valley. One was discovered in Kennewick, Wash., last November.

“It could have serious, detrimental effects on the agricultural industry in Washington,” Zack said.

Researchers are working as fast as they can to develop ways to control the bug if it shows up here in large numbers.

Bug Behavior

At his lab, Lee Ream is trying to understand stink bug behavior: where the bugs will be, at what time of day. It’s an innovative approach that hasn’t been tried elsewhere.

Lee Ream demonstrates a test he’s using tosee how the stink bugs group together.

For example, Ream said, “During the day, the stink bugs might not want to be out in the sun, so they might hide in bushes, but not necessarily in the apple trees. If that’s the case, you don’t want to spray the apples during the day because then they’re not going to get any of the residue, and they’re not going to die.”

Ream is testing that theory. That way he and his colleagues can know when and where to place traps.

Another factor in a successful trap: making sure the traps’ lures work well. Dong Cha, a chemical ecologist with the USDA, uses the stink bugs’ antennae to help create a mixture of chemicals the bugs find attractive.

Cha hooks the antennae to sensors and tests what they can smell. He’s used this technique with other invasive insects, like the African fig fly, which is a problem in Florida.

Then, the researchers put those smells at the end of two tubes and watch where the stink bugs fly.

“If the lure is good it will attract insects,” Cha said. “The hard part is you have to find out what chemicals [the insects smell], and you have to formulate them in a good way to attract the insects.”

They can use those smells the stink bugs like best to create a sort of “roach motel” for the stink bugs, where they will be lured into the traps and pass along poison from the traps to other stink bugs.

Researchers are also looking into how other insects from Asia prey on the stink bugs. They’re testing to see if bringing those insects here would negatively affect the ecosystem.

Michael Bush, an entomologist with Washington State University, said researchers are trying to limit the amount of chemical pesticides growers would have to spray to battle the bugs.

On the East Coast, the bugs cost apple growers $37 million. The growers have had to spray pesticides that don’t just kill one pest. Bush said that kills the beneficial insects, too. He called it a pesticide treadmill.

“We use one pesticide to control a stink bug, and then months later we have to use another insecticide to control aphid outbreaks or mite outbreaks that had been normally controlled by a beneficial insect,” Bush said.

Help From Homeowners

Bush is training homeowners, growers, and master gardeners to spot the brown marmorated stink bug – and to differentiate it from the up to 70 native stink bugs in the area.

“Homeowners tended to know when we had problems with the stink bug before the growers had,” Bush said.

Bush recalled a phone call he received from a Central Washington resident whose family had recently returned from a camping trip in Pennsylvania.

“He noticed that there were these stink bugs crawling on the floor of his garage where he parked his RV. He did fumigate his RV and garage,” Bush said. “But just the story of where he was, and how, on his way back they kept finding these stink bugs in cups and cupboards. … When he did fumigate, he said thousands of these stink bugs came out from underneath the RV.”

Ream sighed and ran his fingers through his thinning hair as he recounted the story.

So far the brown marmorated stink bugs have made it to 40 states. Northwest researchers estimate the bugs will become a bigger problem here in the next three to four years.